Abstract: In order to study the tooth root crack initiation lifes for the helical gears of high-speed EMU， a three-dimensional model of helical gear pair was established using UG software，and the crack initiation positions were determined by ABAQUS.Based on the fatigue cumulative damage theory，nominal stress method and local stress-strain method were used to calculate the crack initiation lifes of the test gears respectively.High-frequency fatigue tests were performed on the test gears to obtain the crack initiation lifes.The simulation results were compared with the test ones to determine the best damage model.The tooth root crack initiation lifes of the helical gears were calculated using the determined model.The influences of factors such as loads， tooth surface roughness， residual stresses， addendum modifications on the crack initiation lifes were analyzed.The research results show that the influences of loads and tooth surface roughness on the crack initiation life are significant， the crack initiation life increases with the increase of residual compressive stresses， proper addendum modifications may improve the crack initiation lifes of the helical gears.

Key words: helical gear；crack initiation life；life prediction；finite element method；high-speed , electric multiple unit（EMU）

摘要： 为分析高速动车组斜齿轮的齿根裂纹萌生寿命，采用UG建模软件建立了斜齿轮副的三维模型，并通过ABAQUS软件确定了裂纹萌生位置。基于疲劳损伤累积理论，对试验齿轮分别采用名义应力法和局部应力应变法模拟计算出裂纹萌生寿命；进行了高频疲劳试验，得到了裂纹萌生寿命，通过对比模拟结果与试验结果，确定了最佳损伤模型，计算得出了斜齿轮齿根的裂纹萌生寿命。分析了载荷、表面粗糙度、残余应力、齿顶修缘等因素对裂纹萌生寿命的影响规律。研究结果表明，载荷及表面粗糙度对裂纹萌生寿命的影响比较显著；裂纹萌生寿命随着残余压应力的增大而延长；适当的修形可延长斜齿轮裂纹萌生寿命。

关键词: 斜齿轮, 裂纹萌生寿命, 寿命预测, 有限元法, 高速动车组